Electrical contact brush biasing arrangement



ELECTRICAL CONTACT BRUSH BIASING ARRANGEMENT N m M A T A Z Filed Dec.51, 1956 INVENTOR, Zoven Aromion,

I I l I 48,633 Patented Aug. 19, 1958 ELECTRICAL CONTACT BRUSH BIASINGARRANGEMENT Zaven Atamian, SliermanOaks, Calif., assignor to HughesAircraft Company, Culver City, Calif., a corporation of Delaware 1Application December 31, 1956, Serial No. 632,625

1 Claim. (Cl. 310-245) This invention finds general utility in the fieldof electrical contact brushes and relates particularly to the type ofelectrical brushes normally employed in commutators and like structures.

In electrical apparatus employing contact brushes, it is common toemploy a spring means for biasing a graphite or like type of brush intocontact with a moving member such as a commutator. The usual practice inthis regard has been to employ either a leaf or a coil type of springacting directly upon the brush element. With these prior knownstructures, constant spring rate was not always available, thus applyingvarying forces to the brush at various positions of the spring. Changesin biasing forces on the brush necessarily alters the contact efliciencyas between the brush and the moving member, this situation beingundesirable in many types of contemporary electrical mechanism.

In another instance, prior electrical contact brush arrangementsemploying coil or leaf springs, due to the presence of even minutequantities of foreign material and/or due to wear on both springcomponents and supporting structure therefor, it has been a commonoccurrence that various portions of the spring mechanism and/ or thesupporting structure for the electrical contact brush would fail tofunction, seize or bind, thus preventing adequate contact between thebrush and the moving member. In many forms of electrical equipment, ahigh degree of reliability must be maintained and such failure of thecontact arrangement cannot be tolerated.

Accordingly, it is one important object of this invention to provide anovel electrical contact brush supporting and biasing arrangement.

Another object of the invention is to provide a novel contact brushbiasing means wherein relatively constant low rate force is applied tothe contact.

A further object of the invention is to provide an electrical contactbrush arrangement having reliable means for biasing the brush intocontact with a moving member and wherein seizing, sticking or binding ofthe elements is reduced to a minimum.

Still another object of the invention is to provide a novel electricalcontact brush arrangement having adjustable spring biasing meansoperatively associated therewith.

Other and further important objects of the invention will becomeapparent from the disclosures in the following detailed specification,appended claim and accompanying drawing, wherein:

Figure 1 is a plan view of the present electrical contact brusharrangement; and

Fig. 2 is a transverse sectional view taken substantially as indicatedby line 22, Fig. 1.

With reference to the drawing, the device hereof includes generally asupporting body 10, a contact brush 11 and biasing means 12. Thesupporting body may be of any desired configuration and includes meansfor supporting both the brush 11 and the biasing means 12. In thepresent instance, the body 16 includes a generally T-shaped groove 13,legs 14 extending substantially laterally in the body 10.

As shown primarily in Fig. 2, a generally square boss 15 is disposedfrom the body 10 and projects into the groove 13. An insulating member16 is carried within the boss 15 and has an elongated opening 17therein. The brush 11, which may be made from any suitable material suchas graphite or the like, is shown as being square in cross section andadapted for longitudinal slidable disposition in the opening 17 in theinsulation I member 16. Obviously, the particular shape of the brush 11is a matter of choice, depending upon particular requirements in variousmechanisms.

The end of the brush 11, remote from the insulation member 16, may beplated as at 18 with any suitable precious metal such as silver or thelike. Thereafter, a laterally extending rod or wire structure 20 issecured to the brush 11 and has end portions 21 that are bent upwardlyfor a purpose to be hereinafter more fully described.

As shown primarily in Fig. 1, a pair of arbors 22 and 23 intersect thelateral portions 14 of the groove 13 and extend through aligned openings25 and into recesses 26 in the body 10. The arbors 22 and 23 haveslotted heads and are adapted to be locked in position by means of setscrews 27 which threadably engage the body 10. The arbors 22 and 23 areadapted to support inner ends of spiral springs 28 and 30 as by means ofpins 31 which extend through openings 32 in the ends of the innersprings. Outer ends of the springs 28 and 30 are adapted for attachmentwith the wire member 20 carried by the free end of the brush 11. Theforce of the springs 28 and 30, acting upon the brush 11, may beindividually adjusted and varied by rotation of the arbors 22 and 23.

It may thus be seen that a dual spring biasing force is simultaneouslyapplied to the brush 11 to urge this brush into constant contact andnormal alignment with a moving surface S. The spring rate of the spiralsprings is very low, thus maintaining a constant force in spite of wearof the contacting end 33 of the brush 11. As shovm in Fig. 1, it may beseen that a contact wire W may be secured as by soldering to the silverplated end 18 of the contact member 11. The wire W may extend to anysuitable point for connection with other apparatus.

It may further be seen that no tendency for the springs to bind will beexperienced due to the fact that a pair of such springs, symmetricallydisposed, are employed to bias the contact member toward the movingsurface. Any even remote tendency of one spring to cause binding will beovercome by the force of the other spring with the possibility of bothsprings failing at the same time being extremely remote.

Having thus described the invention and the present embodiment thereof,it is desired to emphasize the fact that many modifications may beresorted to in a manner limited by a just interpretation of thefollowing clan'n.

- I claim:

An electrical contact brush mounting arrangement comprising, incombination: an elongated brush, rectangular in cross section, disposedfor sliding contact of one axial end with a moving surface; a body forreceiving and longitudinally slidably retaining said brush normal tosaid moving surface; a pair of identical force spiral tension springsdisposed on lateral sides of said brush, axes of said springs beingparallel to said lateral sides of said brush and normal to alongitudinal axis of said brush; a pair of individual arbors attached tosaid springs and disposed in openings in said body for connecting endsof said springs to said body; a plated References Cited in the file ofthis patent UNITED STATES PATENTS Smith Dec. 26, 1871 Van Depoele Feb.25, 1890 Berger Jan. 11, 1938 Welch Nov. 30, 1954 FOREIGN PATENTSGermany Apr. 11, 1938

